That's a good point too. Any KVM switches will be slower. On a PS/2 KVM, you can swap in probably 200 to 350 ms at most. USB is far slower. There may be some enterprise optimized USB KVMs that do it faster but I don't know of any off hand and the cost would obviously be quite higher than a cheap one.

PS/2 was designed for text input. It can handle lots of key presses and lots of keys being hit at once. USB starts to fail and drop keys. PS/2 CAN drop keys and some keys result in multiple key codes being sent, but by and large, PS/2 is superior to USB input for nearly everybody who wants to go the hardware route. Software only on one box? USB may work just fine. But you STILL may run into problems when you hit tons of keys in a short period of time. Considering some "keys" are actually as many as 3 or so keys (alt+shift+f5 as an example) - you can hit the limit real fast if you are in the heat of combat and mashing keys as fast as you can to get that heal off.